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07/16/2019, 5:27 pm EDT

July Global Soil Moisture Outlook

El Nino driven precipitation forecasts are set aside as a possible weak La Nina develops for late northern hemisphere autumn Fig. 1: The global soil moisture anomaly analysis provided by NOAA/CPC valid for June 2019 and annotated 3-month trend by Climate Impact Co. Observational discussion: During the past 3 months the number of large regions of soil moisture change across the globe favored drier conditions (18) versus wetter adjustments (11). Currently, the most profound drought areas stretch across Canada which is mostly unchanged during the past 3 months except drier into Northwest Territories, northern and western Europe which expanded east into Western Russia, a strengthening intense dry region in northeast Russia and ongoing drought which gained intensity since March in southwestern Africa and much of Australia. Central Brazil drought is stronger. Dryness is strong and intensified in Kazakhstan. Possibly the strongest dry change during the past 3 months was in Southeast Asia. The drier changes in parts of Alaska and western Canada is due to a persistent stronger than normal upper level ridge associated with emergence of the positive phase of the Pacific decadal oscillation. The upper ridge extends northwestward and is also the cause of a drier pattern in northeast Russia. The expanding European dryness into Western Russia is due to the strongest anomalous upper ridge of APR/MAY/JUN across the northern hemisphere. A weak El Nino climate accounts for the Southeast Asia dry trend while an emerging positive phase of the Indian Ocean Dipole is associated with drier trends in Western Australia and southeast portions. Anomalous subtropical ridging off the southwest coast of Africa maintains the drought in that region. Wetter conditions were observed in the Central Great Plains and interior western U.S. contributed to by flooding rivers and runoff from snow melt. Northern Argentina also trended wetter during quarter 2 of 2019. A persistent upper trough visiting southeastern Europe caused wetter soil moisture change in that region. The positive phase Indian Ocean Dipole contributed to wetter weather over west/northwest India. In a bit of a surprise, given weak El Nino presence, western Indonesia trended wetter. While crop areas in northeast China observed developing drought in recent months a much wetter trend was notable in southeastern Russia to parts of Japan. Very wet conditions in North-central Russia intensified due to a persistent upper trough during the past several months. Fig. 2: Climate Impact Company 3-month soil moisture outlook. Forecast discussion: The 3-month outlook is based on a trend by ENSO away from El Nino and into neutral phase with borderline La Nina possible by October. All leading global models (CFS V2, NMME and GFDL) are forecasting a possible borderline La Nina for AUG/SEP/OCT 2019. The subsurface equatorial Pacific is cooling! The 90-day outlook valid AUG/SEP/OCT across North America favors drying in the rain-soaked Midwest U.S. while wet weather shifts to the East Coast and possibly the Southeast U.S. The Caribbean Sea to Mexico is forecast to turn wetter. A more robust tropical regime is now anticipated based on the absence of El Nino. In South America the dryness in Brazil worsens and drought is present as spring arrives. Northern Argentina is also likely to trend drier. Western and central Europe drought worsens while wet conditions emerge in far Southeast Europe and far northwestern Russia. Meanwhile just north and east of the Caspian Sea a dry regime is expected. Central and western tropical Africa are wetter which raises the risk of tropical waves moving into the tropical North Atlantic to become hurricanes. Eastern tropical Africa is dry. The South Africa drought continues possibly worsening in Southeast Africa. Normally, Southeast Asia and Indonesia are dry during an El Nino regime. However, the ENSO forecast changes toward borderline weak La Nina which is a wetter scenario for these areas. The widespread Australian drought remains essentially unchanged in the 90-day outlook.